Test Conditions Research Articles

Advanced Analysis of Structural Performance in Novel Steel-Plate Concrete Containment Structures

This paper investigates the structural performance of novel steel-plate concrete containment structures, focusing on third-generation nuclear power plants. To address the challenges of increased complexities and costs associated with double-layer containment designs, this study explores the potential of steel-plate concrete structures to enhance safety, economic efficiency, and construction simplicity. The steel-plate concrete structure, characterized by its core concrete and dual steel plates, shows superior compressive strength, bending resistance, and elastoplasticity. Extensive numerical analyses, including finite element modeling and thermal-stress coupling, were conducted under various load conditions. Under structural integrity test conditions, the maximum radial displacement observed was 24.59 mm. Under design basis conditions, the maximum radial displacement was 47.61 mm; under severe accident conditions, it was 53.83 mm. The ultimate bearing capacity was 0.91 MPa, 2.17 times the design pressure. This study concludes that the steel-plate concrete containment structure maintains a high safety margin under all tested conditions, with stress and strain well within acceptable limits. It can effectively serve as a robust barrier against radioactive leakage and malicious impacts, providing a viable alternative to conventional containment designs.

Optical Target Projector: Principle of Functioning and Basic Performance Test.

Faced with measurement conditions such as high-temperature forging, strict prohibition of surface contamination, and toxic environments, using the projection point of an optical target projector (referred to as an "optical projector") as a photogrammetric target has become a necessary method of high-precision industrial photogrammetry. In connection with the current industrial demand, we have analyzed the principles of optical projectors and introduced their optical characteristics and advantages in the field of industrial photogrammetry. On this basis, a series of tests such as brightness, roundness, and so on were conducted to determine the basic properties of the optical projector. A set of performance test methods including inner coincidence accuracy and outer coincidence accuracy were proposed; the tests included industrial photogrammetry system measurement repeatability, surface measurement precision, and a comparison test with laser tracker. The test conditions used optical projection points as the photogrammetry targets. The test results showed that the coordinate measurement repeatability of the industrial photogrammetry system is 0.010 mm, and the surface measurement precision is 0.007 mm under the condition of a single optical projector station, with little difference between the results under the condition of pasting retro-reflective targets. In the process of the comparison test with laser tracker, the image quality of the black measurement object obtained is obviously inferior to other surfaces, so the analysis of the point projector is greatly affected by the color of the measured object and other conditions, which provides a reference for the measurement object and application range of the industrial photogrammetric system based on optical targets. The results demonstrate the applicability and reliability of using the optical projection point of an optical projector as target points for photogrammetry.

Report of RILEM TC 281-CCC: A critical review of the standardised testing methods to determine carbonation resistance of concrete

The chemical reaction between CO2 and a blended Portland cement concrete, referred to as carbonation, can lead to reduced performance, particularly when concrete is exposed to elevated levels of CO2 (i.e., accelerated carbonation conditions). When slight changes in concrete mix designs or testing conditions are adopted, conflicting carbonation results are often reported. The RILEM TC 281-CCC ‘Carbonation of Concrete with Supplementary Cementitious Materials’ has conducted a critical analysis of the standardised testing methodologies that are currently applied to determine carbonation resistance of concrete in different regions. There are at least 17 different standards or recommendations being actively used for this purpose, with significant differences in sample curing, pre-conditioning, carbonation exposure conditions, and methods used for determination of carbonation depth after exposure. These differences strongly influence the carbonation depths recorded and the carbonation coefficient values calculated. Considering the importance of accurately determining carbonation potential of concrete, not just for predicting their durability performance, but also for determining the amount of CO2 that concrete can re-absorb during or after its service life, it is imperative to recognise the applicability and limitations of the results obtained from different tests. This will enable researchers and practitioners to adopt the most appropriate testing methodologies to evaluate carbonation resistance, depending on the purpose of the conclusions derived from such testing (e. g. materials selection, service life prediction, CO2 capture potential).

Activity of antibiotics against Burkholderia cepacia complex in artificial sputum medium.

Burkholderia cepacia complex (Bcc) is a collection of intrinsically drug-resistant Gram-negative bacteria that cause life-threatening disease in people with cystic fibrosis (CF). Standard antimicrobial susceptibility testing methods have poor predictive value for clinical outcomes in Bcc infections, probably due in part to differences between in vitro testing conditions and the environment in which Bcc grow in the lungs of people with CF. To compare the activity of commonly used antibiotics under standard in vitro testing conditions with activity in conditions mimicking those found in vivo. Two Bcc strains were grown alone and with six different antibiotics (minocycline, ceftazidime, meropenem, tobramycin, levofloxacin, trimethoprim-sulfamethoxazole) in two different media: standard cation-adjusted Mueller-Hinton broth and an artificial sputum medium designed to simulate the environment in the lungs of people with CF through addition of components including mucin, free DNA and amino acids. Two different starting conditions were used for time-kill assays: a standard ∼5 × 106 cfu/mL inoculum, and a high-density inoculum in which bacteria were grown for 72 hours before addition of antibiotics. Growth detection was performed by colony enumeration and by detection of resazurin reduction. There were major discrepancies between standard susceptibility results and activity in our models. Some antibiotics, including ceftazidime, showed minimal activity in all time-kill assays despite low minimal inhibitory concentrations, while others, notably tobramycin, were more active in high-density growth conditions than in standard time-kill assays. This work underscores the urgent need to develop more clinically relevant susceptibility testing approaches for Bcc.

Development of a large diameter invitro flow loop thrombogenicity test system.

To accommodate a wider range of medical device sizes, a larger invitro flow loop thrombogenicity test system using 9.5 -mm inner diameter (ID) tubing was developed and evaluated based on our previously established 6.4 -mm ID tubing system. Four cardiopulmonary bypass roller pumps were used concurrently to drive four flow loops during testing. To ensure that each pump produced a consistent thrombogenic response for the same material under the same test conditions, a novel dynamic roller occlusion setting method was applied. Five materials with varying thrombogenic potentials were tested: polytetrafluoroethylene (PTFE), silicone, 3D-printed nylon, latex, and nitrile rubber (BUNA). Day-old bovine blood was heparinized to a donor-specific concentration and recirculated through the flow loops containing test materials at 20 rpm for 1 h at room temperature. Material thrombogenicity was characterized by measuring the thrombus surface coverage, thrombus weight, and platelet (PLT) count reduction. The larger tubing system can differentiate thrombogenic materials (latex, BUNA) from the thromboresistant PTFE material. Additionally, silicone and the 3D-printed nylon exhibited an intermediate thrombogenic response with significantly less thrombus surface coverage and PLT count reduction than latex and BUNA but more thrombus surface coverage than PTFE (p < 0.05). The 9.5 -mm ID test system can effectively differentiate materials of varying thrombogenic potentials when appropriate pump occlusion settings and donor-specific anticoagulation are used. This system is being assessed in an interlaboratory study to develop standardized best practices for performing invitro dynamic thrombogenicity testing of medical devices and materials.

The Influence of Oil and Thermal Aging on the Sealing Characteristics of NBR Seals.

Nitrile Butadiene Rubber (NBR) is widely used as a sealing material due to its excellent mechanical properties and good oil resistance. However, when using NBR material, the seal structure is unable to avoid the negative effects of rubber aging. Hence, the influence of oil and thermal aging on the characteristics of NBR seals was studied by coupling the mechanical behavioral changes with the tribological behavioral changes of NBR in oil and the thermal environment. For this paper, aging testing and compression testing of NBR were carried out. Additionally, friction testing between friction pairs under different aging times was carried out. The surface morphology of the NBR working surface under different aging conditions was also observed. Finally, coefficients of different test conditions were introduced into the finite element model of NBR seals. It can be seen from the results that the elastic modulus increased with the increase in aging time in the thermal oxidative aging testing. The elastic modulus after 7 days of thermal oxidative aging increased by 135.45% compared to the unaged case, and the elastic modulus after 7 days of oil aging increased by 15.03% compared to the unaged case. The compression set rate of NBR increased significantly with the increase in aging time and temperature. The coefficient of friction (COF) between friction pairs increased first and then decreased with the increase in aging time. The maximum contact pressure decreased by 2.43% between the shaft and sealing ring and decreased by 4.01% between the O-ring and groove. The proportion of the effective sealing area decreased by 3.05% between the shaft and sealing ring and decreased by 6.11% between the O-ring and groove. Furthermore, the sealing characteristics between the O-ring and groove were better than those between the shaft and sealing ring.

Thermodynamic approach for designing processing routes of 4Mn quenching and partitioning steel

AbstractThe study addresses the design and optimization of chemical composition and processing routes of new quenching and partitioning medium-Mn alloy using theoretical and experimental approaches. The thermodynamic calculations using Thermo-Calc and JMatPro software were carried out to characterize the influence of Mn, Si and Al contents on cementite formation and precipitation processes. The evolution of individual phases as a function of temperature under thermodynamic equilibrium conditions was estimated. The investigations included the determination of continuous cooling transformation (CCT) and the time–temperature transformation (TTT) diagrams of a model 4Mn alloy. The calculated equilibrium diagrams were compared with the experimental diagrams determined using dilatometric tests. Microstructural observations were carried out to verify the results of dilatometric measurements. The results of thermodynamic calculations and experimental tests showed the moderate agreement. It is related to the inaccuracy of currently available models in the used software and/or non-equilibrium conditions of experimental tests.

Nondestructive Fatigue Life Prediction for Additively Manufactured Metal Parts through a Multimodal Transfer Learning Framework

Understanding the fatigue behavior and accurately predicting the fatigue life of laser powder bed fusion (L-PBF) parts remain a pressing challenge due to complex failure mechanisms, time-consuming tests, and limited fatigue data. This study proposes a physics-informed data-driven framework, a multimodal transfer learning (MMTL) framework, to understand process-defect-fatigue relationships in L-PBF by integrating various modalities of fatigue performance, including process parameters, XCT-inspected defects, and fatigue test conditions. It aims to leverage a pre-trained model with abundant process and defect data in the source task to predict fatigue life nondestructively with limited fatigue test data in the target task. MMTL employs a hierarchical graph convolutional network (HGCN) to classify defects in the source task by representing process parameters and defect features in graphs, thereby enhancing its interpretability. The feature embedding learned from HGCN is then transferred to fatigue life modeling in neural network layers, enabling fatigue life prediction for L-PBF parts with limited data. MMTL validation through a numerical simulation and real-case study demonstrates its effectiveness, achieving an F1-score of 0.9593 in defect classification and a mean absolute percentage log error of 0.0425 in fatigue life prediction. MMTL can be extended to other applications with multiple modalities and limited data.

Real-time energy management simulation for enhanced integration of renewable energy resources in DC microgrids

The presented work addresses the growing need for efficient and reliable DC microgrids integrating renewable energy sources. However, for the sake of practicality, implementing complex control strategies can increase system complexity. Thus, efficient methodologies are required to provide efficient energy management of microgrids while increasing the integration of renewable energy sources. The primary contribution of this work is to investigate the issues related to operating a DC microgrid with conventional control designed to power DC motors using readily available, non-advanced control strategies with the objective of achieving stable and reliable grid performance without resorting to complex control schemes. The proposed microgrid integrates a combination of uncontrollable renewable distributed generators (DGs) alongside controllable DGs and energy storage systems, including batteries and supercapacitors, connected via DC links. The Incremental Conductance (InCond) algorithm is employed for maximum power point tracking to maximize power output from the PV system. The energy management strategy prioritizes the solar system as the primary source, with the battery and supercapacitor acting as backup power sources to ensure overall system reliability and sustainability. The effectiveness of the microgrid under various operating conditions is evaluated through extensive simulations conducted using MATLAB. These simulations explore different power generation scenarios, including normal operation with varying load levels and operation under Standard Test Conditions (STC). Moreover, fault analysis of the DC microgrid is performed to examine system reliability. The system performance is evaluated using real-time simulation software (OPAL-RT) to validate the effectiveness of the approach under real-time conditions. This comprehensive approach demonstrates the efficacy of operating a DC microgrid with conventional controllers, ensuring grid stability and reliability across various operating conditions and fault scenarios while prioritizing the use of renewable energy sources. The results illustrated that system efficiency increases with load, but fault tolerance measures, can introduce trade-offs between reliability and peak efficiency.

Femtosecond laser writing of durable open microfluidic channels via a mode-switchable strategy

Open microfluidic systems offer significant advantages, including the elimination of external pumps and facilitating fluid access at any point along the channel. However, their deployment in harsh environments is commonly compromised due to the delicate nature of hydrophilic chemical coatings and the vulnerability of open microchannels to clogging and contamination. Here, a bioinspired, demand-responsive mode-switchable strategy is proposed to enhance the mechanical durability of open microfluidic systems. Specifically, under harsh conditions or when long-term storage is necessary, this strategy allows the open microfluidic device to transition to a protective mode simply through releasing the strain, thereby preserving the integrity of the structure and hydrophilic coatings. The stretched open microfluidic mode enables spontaneous liquid spreading along a hydrophilic microchannel scribed by femtosecond laser. This mode-switchable strategy provides the open microfluidic device with robustness to maintain spontaneous liquid flow, even under severe testing conditions such as 2000 cycles of cotton swab rubbing, sand impact, sandpaper abrasion, tape peeling, twisting, and finger rubbing. A proof-of-concept application involving blood type analysis on this mode-switchable open microfluidic device showcases its superior mechanical durability under severe environmental conditions. The proposed strategy paves the way for the broader use of open microfluidic devices in various practical applications.

Evaluation of Tibiofemoral Contact Mechanics After a Novel Hybrid Procedure for Femoral Osteochondral Defect Repairs With a Subchondral Implant and Dermal Matrix.

There is a lack of procedures that adequately address the subchondral bone structure and function for reconstructing osteochondral defects in the femoral condyles. To biomechanically evaluate the tibiofemoral joint contact characteristics before and after reconstruction of femoral condylar osteochondral defects using a novel hybrid reconstructive procedure, which was hypothesized to restore the contact characteristics to the intact condition. Controlled laboratory study. Tibiofemoral contact areas, contact forces, and mean contact pressures were measured in 8 cadaveric knees (mean age 52 ± 11 years; 6 women, 2 men) using a custom testing system and pressure mapping sensors. Five conditions were tested for each condyle: intact, 8-mm defect, 8-mm repair, 10-mm defect, and 10-mm repair. Medial femoral condylar defects were evaluated at 30° of knee flexion and lateral condylar defects were evaluated at 60° of knee flexion, with compressive loads of 50, 100, and 150 N. The defects were reconstructed with a titanium fenestrated threaded implant countersunk in the subchondral bone and an acellular dermal matrix allograft. Repeated-measures analysis of variance with Bonferroni correction for multiple comparisons was used to compare the results between the 5 testing conditions at each load. Medial condylar defects significantly increased mean contact pressure on the lateral side (P < .042), which was restored to the intact levels with repair. The lateral condylar defect decreased the mean contact pressure laterally while increasing the mean pressure medially. The lateral and medial mean contact pressures were restored to intact levels with the 8-mm lateral condylar defect repair. The medial mean contact pressure was restored to intact levels with the 10-mm lateral condylar defect repair. The lateral mean contact pressure decreased compared with the intact state with the lateral condylar 10-mm defect repair. Tibiofemoral joint contact pressure was restored to the intact condition after reconstruction of osteochondral defects with dermal allograft matrix and subchondral implants for the repair of both 8- and 10-mm lateral condylar defects as well as 8-mm medial condylar defects but not completely for 10-mm medial condylar defects. The novel hybrid procedure for osteochondral defect repair restored tibiofemoral joint contact characteristics to normal in a cadaveric model.

Experimental Characterization on Injection and Spray of Coal-Derived Liquid Fuel

Coal-derived liquid fuels (CDLs) are petroleum diesel’s (PD) alternatives produced by coal liquefaction. The injection and non-evaporating spray characteristics of CDLs, including diesel from direct coal liquefaction (DDCL), diesel from indirect coal liquefaction (DICL), and their blends (DBCL), were discussed. The high-pressure common rail test bench was used to evaluate the injection delay, injection rate, injection quantity, single injection heat value, and injector inlet pressure. A constant volume chamber along with high-speed camera was used to visualize the spray, then measuring the spray tip penetration distance, spray cone angle, and spray area. Besides, injection tests were conducted using injectors removed from engines that had finished durability tests fueled with DBCL and PD. The results revealed that DDCL had shorter injection delays and more mass injection quantity than PD, with an injection heat value 7% higher at a rail pressure of 140 MPa. Regarding the spray, PD had a longer spray tip penetration distance and smaller cone angle than CDLs. On test conditions, the spray Sauter mean diameters of DDCL and DICL were over 30% less than that of PD. Inferring from the reduction in injection rate and quantity, PD generated more clog in the injector hole than DBCL.

Enhancing Commercial Check Valves in Downhole Pump Applications through Laboratory Testing System Development

In this study, we aim to enhance the performance and longevity of downhole pumps employed in crude oil extraction in the oil industry. Downhole pumps play a pivotal role in the rod-pump system, comprising traveling and standing valves that function similarly to ball check valves. However, these valves often experience premature wear and tear. To address this concern, we embarked on experiments involving various check valve alternatives to conventional ball valves within downhole pumps. The testing conditions were controlled precisely. Furthermore, we evaluated four distinct check valve types, the original (representing the incumbent ball valves), spring-poppet (C), spring-ball (CB), and spring-poppet with soft-seated (S6C) check valves, within a controlled laboratory environment. We employed a TEXAPON N70 solution to replicate the properties and temperature conditions of crude oil. A portable ultrasonic flow meter was used to quantify the pump flow rate and assess its volumetric efficiency. In addition, we recorded data on the polished-rod load and plunger displacement to generate dynamometer cards, thereby enabling a comprehensive evaluation of the operational performance of the pump. Furthermore, we conducted a vacuum test to scrutinize valve leakage, which is a crucial indicator of the operational lifespan of a downhole pump. Our findings show that incorporating the CB check valve with the RHB pump in oil wells operated by the PTT Exploration and Production Public Company Limited (PTTEP) could result in a 15% increase in volumetric efficiency and a remarkable 160% improvement in durability compared to the original ball check valve.

Impact of cryogenic aging and test-environment on mechanical properties and tribological performance of PI-based materials

This study investigates the effect of test-environment, temperature, and cryogenic aging in liquid nitrogen for 5 months on mechanical and tribological performance of polyimide (PI) and PI composites. Tribological tests were conducted at 25 °C in air, and at both 25 °C and −100 °C in a high vacuum (10-5 Pa) environment. Impact of cryogenic aging, testing condition on PI-based materials varied depending on the polymer structure and composition. Cryogenic aging led to embrittlement, increasing the coefficient of friction and wear rate up to 77 % and 165 %, respectively. Some polyimides exhibited the lowest coefficient of friction (0.04) in vacuum at 25 °C, while the temperature reduction to −100 oC in vacuum generally decreased the tribological performance, increased contact stresses and abrasive wear of the materials.

Effects of inlet air holes on swirl flow characteristics and outlet temperature distribution in an axial swirl combustor

The air inlet holes on the swirl combustor are crucial for high-performance micro gas turbine (MGT), affecting internal airflow, fuel-air mixing, temperature distribution, and cooling. However, there are seldom studies that pay attention to the influence of the air inlet holes coupled with low volatility macromolecular fuels for fast and better fuel-air mixing and combustion processes in MGT. This study investigates the influence of primary and dilution hole positions on airflow, temperature, emissions, and combustion efficiency. Numerical simulations in ANSYS Fluent examine five inlet hole configurations in a two-stage axial swirl combustor. Simulation validation is conducted under three test conditions. The results showed that the cut-off effect of the primary hole affected the size of the swirl vortex core, and the backward movement of the primary hole resulted in a significant increase in the length of the recirculation zone and the coherence high-temperature zone, accelerated the droplet evaporation rate, and reduced CO and NO emissions. Backward movement of dilution hole alters flow field, affecting swirl vortex stability and reflow intensity. Case 3, with original dilution hole and backward extended primary hole, exhibits optimal outlet temperature distribution and combustion efficiency.

Creep properties of heat-resistant ultrafine-grained Al (HITEMAL©) determined by small punch testing

The creep properties of thermally stable ultrafine-grained Al metal matrix composite strengthened and stabilized by continuous in situ amorphous Al2O3 network (named HITEMAL©) prepared by powder metallurgy (PM) were tested by small punch creep testing (SPCT) in the temperature range from 573 to 673 K. The experimental SPCT results were correlated and compared with the results obtained by conventional tensile creep testing. The mutual correlation between tensile and SPCT creep results based on the transition stress was proposed and used to correctly interpret the measured SPCT data. The creep behaviour of HITEMAL© is characterized by the high values of apparent stress exponents and by the presence of transition stress at which the apparent stress exponents significantly changed. The SPCT discs fractured by the radial cracks at low values of deflection with only limited creep deformation highly localized in the vicinity of the fracture surfaces. The detailed analysis of fractured SPCT discs by scanning electron microscopy showed ductile dimpled fracture surfaces with the presence of unusual high filament-like tearing edges. The comparison of obtained results with other PM Al-based alloys and composites confirmed a significantly higher creep performance of HITEMAL© at used testing conditions.

Hierarchical Predictive Optimal control for Range Extension of EV with ANN based Torque Control for IPMSM drives

This study presents a novel methodology to enhance the energy efficiency of Electric Vehicles (EVs) while maintaining dynamic stability and driving comfort, even on uneven roads, using onboard vehicle measurements. The approach involves a hierarchical control scheme that integrates a model predictive controller with a torque vectoring algorithm to optimize torque demand and accurately anticipate road-specific torque requirements. The control is implemented on EV with Interior Permanent Magnet Synchronous Motors (IPMSM) as four wheel drives. The optimal torque control is realised through an Artificial Neural Network (ANN)- based motor torque control scheme. The design is validated through tests in real-world driving scenarios. In comparison with conventional methods, the proposed method shows a 37% increase in energy efficiency across different test conditions, thereby resulting in an increase in EV driving range. These advancements are achieved without substantial modifications to the EV’s drivetrain, representing a significant step forward in sustainable and efficient electric mobility.

5G Networks Based on Software Defined Network

A software-defined network (SDN) based 5G architecture that utilizes three controllers to improve network performance is proposed in this paper. The controllers are responsible for managing functions related to access mechanism, core connectivity, and network transport. The proposed architecture aims to address solutions for the challenges of traditional 5G networks such as scalability, flexibility, and resource allocation. The paper investigates two networks: 5G without SDN and 5G with SDN. The performance of these networks is evaluated by simulation tests using OMNeT++. The results show a considerable improvement in performance measures such as throughput, packet error rate (PER), and energy consumption. Under favorite test conditions, improvements of 46%, 88% and 94%, in throughput, PER, and energy consumption are achieved. The main finding of the paper is that the proposed SDN-based 5G architecture with multi-controllers is a promising arrangement to overcome the challenges of 5G networks.

Ce-doped cobalt-based hydroxide assisted with low-temperature molten salt for industrial oxygen evolution reaction

Developing low cost and high-performance oxygen evolution electrocatalysts is significant to improve the efficiency of water electrolysis for large-scale hydrogen production. Cobalt hydroxide is a promising electrocatalyst for oxygen evolution reaction (OER), but its poor conductivity and activity seriously restrict the practical application. A simple one-step low temperature molten salt method was applied to successfully synthesize the Ce-doped cobalt hydroxide nitrate (Ce-CoNH/CF), which exhibits outstanding OER performance with a low overpotential of 448 mV at the current density of 1000 mA/cm2 in 1 mol/L KOH. The remarkable performance of Ce-CoNH/CF electrode in OER may be the comprehensive result of fast reaction kinetics, large electrochemical active specific surface area (ECSA) and small charge transfer resistance (Rct) as revealed by the Tafel, cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) analysis. Under the simulated industrial test conditions (6 mol/L KOH, 70 °C), the Ce-CoNH/CF electrode still displays excellent OER performance.

Impinging ceiling flame behaviors induced by wall-attached gaseous fuel fires at one end in a narrow building corridor: Different phases and generalized correlations

This work investigated the flame extension behavior after impinging upon a ceiling induced by wall-attached fires at the closed end in a narrow building corridor. Experiments were conducted in a reduced scale corridor with one end closed and the other opened, under various fire heat release rates and source-ceiling heights (from 0.05 m to 0.50 m) of totally 353 test conditions. The flame morphological characteristic parameters involving the flame extension length in the center of the ceiling and in the two sides were measured and analyzed comprehensively. By a careful observation, it was found that, as the fire heat release rate increased or the source-ceiling height decreased, the ceiling flame extension behavior can be divided into different behavior phases: the flame spreads to the two sides after impinging the narrow building ceiling; flame extends longitudinally after reaching side walls, presenting a semi-elliptical shape; flame in the two sides extends farther than that in the center of the ceiling, presenting a “U” shape; and flame presents a cellular structure (the fire source is near the building ceiling). The dimensionless critical fire heat release rates for the transition of these phases were identified, and non-dimensional correlations were obtained for the prediction of flame extension lengths of different phases. This work provides new observations of different phases and generalized correlations for impinging ceiling flame behaviors induced by wall-attached gaseous fuel fires at one end in a corridor.